The present invention relates to methods and apparatus for maintaining uniform sound volume of television receivers and audio systems, and more particularly such receivers and systems when using a successive multichannel regime in a television set and successive audio broadcasts on audio systems.
Television sets have buttons on the front panel and on a remote control device that are used to change television stations and the volume of sound coming from the television set for both regular or cable stations. It is well known that there is a problem in the variation of the loudness of sound emanating from a television set when the viewer/listener changes channels. The variation of sound from different channels of broadcasting is typically up to plus or minus twenty or twenty-five per cent. The reason for the variation is that the volume of the audio signal is a product of (i) the amplitude of the incoming sound signal and (ii) the amplification of the signal during its path in the television receiver. The amplitude of the sound signals on different channels is often not the same because of many factors including the fact that the signals come from different countries and regions where there is a variance in quality of retranslating, differences between cable companies, differences in the television disposition of the satellite antenna and other factors. Accordingly, it is impossible beforehand to determine the correct loudness of the sound heard by the user and simply incorporate that sound level into the memory of the television set. In addition, different individuals might have different preferred sound levels.
In the prior art attempts have been made to address this problem. For example, U.S. Pat. No. 5,631,714 to Saadoun is a system for automatically adapting the mean sound level of a television receiver involving both video and audio signals. The sound level of the signals are adjusted on the television receiver. Saadoun has several drawbacks. For example, one characteristic of the system in Saadoun is that the manufacturer of the television set must determine the average user""s preferred level of sound volume at the point of manufacture in the factory and then build that into the system. This characteristic results in two drawbacks. First, individual preferences for preferred sound volume may vary and adequate consideration for this would not be provided by the system of Saadoun. In addition, even the same individual may need to vary his or her preferred sound volume depending on mood, time of day, etc. Second, the incoming audio signals differ in volume depending upon which country or region in the world they are sent from. It would be cumbersome for different settings to have to be made for each possible source of audio signal in the world.
An additional characteristic of Saadoun that does not adequately address the problem of variations in sound volume is that in its system the audio signals are adjusted at the point of their entry into the television set rather than at the point of output from the television to the ears of the listener/viewer. At the point of input there is a smaller magnitude of variations in sound volume from different channels of broadcasting than there is at the point of output. This is because the difference between the level of sound on different channels of broadcasting grows substantially after the audio signal passes the amplifying path of the television set and remote control device. Accordingly, creating uniformity at the point of the input of the television set would not solve the problem completely because there would likely be at least some minute variations in sound volume remaining and these remaining variations would then be magnified after the audio signal passes the amplifying path of the television set and travels to the ear of the listener/user.
Another characteristic of Saadoun that does not adequately address the problem of variations in sound volume is that the system of Saadoun may not be capable of adjusting the sound level for very high sound volumes coming from a new channel. Finally, the system in Saadoun does not achieve an acceptable degree of uniformity of sound.
U.S. Pat. No. 4,238,766 to Masuda is a channel level adjusting apparatus for equalizing the amplitude level of received television signals of a plurality of channels. Masuda utilizes band pass filters and circuits that shift the phase of the signals and that adjust the signals on the input of the television receiver.
What is needed is a method and apparatus for achieving uniform sound volume coming from a television set or audio system that is effective regardless of the source of the television signal, that allows the user""s sound volume preferences to be considered, that operates on the output of the television receiver, is not cumbersome, is effective for volume deviations likely to be found in any television set, is simple to construct and is simple for the user to use. The present invention attains all of these features and more and is applicable also to other audio systems.
The following important objectives and advantages of the present invention are:
(1) to provide a method and apparatus for maintaining uniform sound volume heard from any station of a television set or other audio system,
(2) to provide such a method and apparatus of maintaining uniform sound volume of a television without having to determine at the point of manufacture what the preferred volume of a typical user is but rather by allowing the individual user to select that user""s preferred sound volume,
(3) to provide such a method and apparatus that allows the same individual to achieve uniformity of sound volume at a different level of volume depending upon the time of day, the individual""s mood or other subjective or individual factors,
(4) to provide a method and apparatus of maintaining uniform sound volume where the user of the audio system fitted with the apparatus of the present invention can select a preferred volume by hitting on a single occasion a single button on the outside panel of the television set or other audio system or on the remote control device,
(5) to provide a method and apparatus of maintaining uniform sound volume of signals from a television set on any channel wherein the audio signals are adjusted at the point of output to the ears of the listener/user after passing the amplifying path of the television set rather than being adjusted at the point of the signal""s input into the television set,
(6) to provide a method and apparatus of maintaining uniform sound volume of the television set that operates effectively regardless of whether the change in loudness is upward or downward and one that is effective for the spectrum of deviations likely to be heard on a television set with many channels,
(7) to provide such a method and apparatus that is easy to use,
(8) to provide such a method and apparatus that is easy to manufacture and not cumbersome,
(9) to provide a method and apparatus of maintaining uniform sound volume where the user""s pushing of the START button on the television set or other audio system having the apparatus, or on the remote control device, causes a voltmeter to measure the level of the preferred or first volume of the tension on the output of the amplifier of the sound, which tension is proportionate to the sound""s loudness, and to transmit that level to the RAM memory of a digital signal processor for storage,
(10) to provide a method and apparatus of maintaining uniform sound volume where the measurement of the preferred volume of the tension on the output of the amplifier of sound occurs by measuring a series of between approximately 5 and 10 volumes of this tension at definite intervals without disturbing the user and whereby the digital signal processor then calculates the mean value of these measured volumes to create the first volume of the tension that is stored,
(11) to provide a method and apparatus of maintaining uniform sound volume where the measurement of the second and subsequent volume of the tension occurs in two stagesxe2x80x94first a crude estimate from one or two measurements to quickly adjust the sound volume toward the preferred sound volume level and then by measuring a further series of between approximately 5 and 10 volumes of the tension on the output of the sound amplifier located in the audio system at definite intervals to create a refined second or subsequent volume of the tension which is used to further adjust the volume to the preferred volume of the tension without disturbing the user,
(12) to provide such a method and apparatus of maintaining uniform sound volume from television signals regardless of the station chosen or content of the station wherein when the user subsequently switches to a second or subsequent channel the apparatus switches on and the voltmeter measures the volume of the tension of the second channel at a number of intervals, the digital signal processor calculates the mean level and once again transmits that mean volume of the tension to the RAM and wherein the digital signal processor calculates the difference between the preferred volume of the tension previously stored and the level of the tension of the second or subsequent channel and if there is a difference in volumes of tension between the two, sends an order to adjust the volume until the difference between the two becomes zero, and
(13) to provide such a method and apparatus wherein the digital signal processor turns the apparatus off after the volume of the tension is adjusted or after the digital signal processor determines that there is no need to adjust the volume.